Journal of Hydraulic Research最新文献

{"title":"Assessment of interfacial turbulence treatment models for free surface flows","authors":"Pengxu Zou, Taeksang Kim, Jeremy D. Bricker, Wim S.J. Uijttewaal","doi":"10.1080/00221686.2023.2246925","DOIUrl":"https://doi.org/10.1080/00221686.2023.2246925","url":null,"abstract":"The modelling of complex free surface flows is challenging due to the mobility and deformability of the interface and air entrainment characteristics, which are highly affected by turbulence. With the framework of Reynolds averaged Navier–Stokes (RANS) models and the volume of fluid (VOF) method, turbulence quantities at the air–water interface tend to be over-estimated. In this study, interfacial turbulence treatment methods including the buoyancy modification model based on the simple gradient diffusion hypothesis (SGDH) and Egorov’s turbulence damping model are investigated. Furthermore, due to the unconditionally unstable characteristics of the standard k-ε turbulence model, the stabilized k-ε turbulence model is applied as a comparison. The turbulence attenuation performance using different interfacial turbulence treatment methods in the vicinity of the interface is compared and discussed for stratified flows and free overflow weirs for aerated and non-aerated nappe scenarios. The turbulence quantities and free surface profile under different flow conditions are validated against experimental data and an analytical model. The results show that for free surface waves, both the SGDH model and the turbulence damping model give strong improvements in turbulence production compared with the standard k-ε model. The SGDH model augments the turbulence kinetic energy (TKE) in the unstable stratification, leading to unphysical behaviour for the partially dispersed and separated flow.","PeriodicalId":54802,"journal":{"name":"Journal of Hydraulic Research","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134947723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation of laminar to transitional wakes past cylinders with a discontinuous Galerkin inviscid shallow water model","authors":"Xitong Sun, Georges Kesserwani, Mohammad Kazem Sharifian, Virginia Stovin","doi":"10.1080/00221686.2023.2239750","DOIUrl":"https://doi.org/10.1080/00221686.2023.2239750","url":null,"abstract":"Laminar to transitional wakes occur in slow, quasi-steady flows past cylinders at low cylinder Reynolds numbers (Red ≤ 250). Inviscid numerical solvers of the depth-averaged shallow water equations (SWE) introduce numerical dissipation that, depending on Red, may imitate the mechanisms of viscous turbulent models. However, the numerical dissipation rate in a second-order finite volume (FV2) SWE solver is so large at a practical resolution that this can instead hide these mechanisms. The extra numerical complexity of the second-order discontinuous Galerkin (DG2) SWE solver results in a lower dissipation rate, making it a potential alternative to the FV2 solver to reproduce cylinder wakes. This paper compares the DG2 and FV2 solvers, initially for wake formation behind one cylinder. The findings confirm that DG2 can reproduce the expected wake formations, which FV2 fails to capture, even at a 10-fold finer resolution. It is further demonstrated that DG2 is capable of reproducing key features of the flow fields observed in a laboratory random cylinder array.","PeriodicalId":54802,"journal":{"name":"Journal of Hydraulic Research","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134947725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Closure to “Numerical investigation of air demand by the free surface tunnel flows” by WANGRU WEI, JUN DENG and WEILIN XU, <i>J. Hydraulic Res.</i> 59(1), 2021, 158–165, https://doi.org/10.1080/00221686.2020.1744747","authors":"Wangru Wei, Jun Deng, Weilin Xu","doi":"10.1080/00221686.2023.2262301","DOIUrl":"https://doi.org/10.1080/00221686.2023.2262301","url":null,"abstract":"\"Closure to “Numerical investigation of air demand by the free surface tunnel flows” by WANGRU WEI, JUN DENG and WEILIN XU, J. Hydraulic Res. 59(1), 2021, 158–165, https://doi.org/10.1080/00221686.2020.1744747.\" Journal of Hydraulic Research, 61(5), pp. 807–808 Disclosure statementNo potential conflict of interest was reported by the author(s).NotationA*=dimensionless air vent parameter (–)Fr=flow Froude number (–)ht=tunnel height (m)Lt=tunnel length (m)","PeriodicalId":54802,"journal":{"name":"Journal of Hydraulic Research","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134949482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bed morphology adjustment under the impact of a near-bank emergent model vegetation patch","authors":"Xu-Feng Yan, Huan-Feng Duan, Wing-Hong Onyx Wai, Xie-Kang Wang","doi":"10.1080/00221686.2023.2241844","DOIUrl":"https://doi.org/10.1080/00221686.2023.2241844","url":null,"abstract":"ABSTRACTThis paper investigated spatial characteristics of bed morphology around a near-bank emergent vegetation patch. Experimental results showed that patch length and density impacted the spatial scale, orientation and type of pool-bar morphology around the patch. Adjacent to the patch, the pool onset lowest location tended to move upstream as patch length and density increased, quantitatively described by a power function involving the two factors; the transverse bed topography along the pool was described by a two-zone scaling model, providing prediction models for the pool morphology, particularly for narrow urban channels. Moreover, we identified, in the patch wake, two types of bars formed meditated by patch length. Short-point and elongated bars formed under short and long patches, respectively, attributed to different mechanisms of flow–sediment-patch interaction, offering new insights into wake depositional trends and streamwise vegetation succession during different vegetation growth stages. The gained knowledge is useful for vegetation-based urban channel restoration.KEYWORDS: Flow–sediment–vegetation interactionnear-bank vegetation successionpool-bar morphologysecondary flowssimilarity in bed topography Supplemental dataSupplemental data for this article can be accessed online at https://doi.org/10.1080/00221686.2023.2241844.Data availabilityMost figures can be generated from data deposited at https://doi.org/10.5281/zenodo.4993413Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis research was partially supported by the National Natural Science Foundation of China (nos. 52239006 and 51909178), the Fundamental Research Funds for the Central Universities, Sichuan University (2020SCU12064) and the RGC project (Polyu 152743/16E), Hong Kong; The research project from the Hong Kong Polytechnic University; CRSRI Open Research Program.","PeriodicalId":54802,"journal":{"name":"Journal of Hydraulic Research","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134948810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the dynamics of gravity current motion in a stratified ambient","authors":"Angelos Kokkinos, Panagiotis Prinos","doi":"10.1080/00221686.2023.2239749","DOIUrl":"https://doi.org/10.1080/00221686.2023.2239749","url":null,"abstract":"AbstractThis study presents LES results of lock-release propagating gravity current (GC) at the base of a linearly stratified ambient. The focus of the study is to investigate the effect of ambient stratification on GC motion for both subcritical and supercritical regimes. The effects of Reynolds number and the ratio of the fluid depth in the lock to the total ambient fluid depth on GC front velocity are also examined. Also, the effect of stratification strength on mixing is evaluated. It is found that both subcritical and supercritical GCs have a constant-velocity phase. This phase terminates due to the current interaction with the internal waves (IWs) for the former, while for the latter, it is due to the decay of the head buoyancy. The duration of the constant-velocity phase increases with increasing stratification strength when the current is supercritical. For weak stratification the turbulence is considerable, while it is suppressed with stronger stratification. Mixing is more intense for supercritical GCs; however, mixing efficiency is much higher for subcritical GCs.Keywords: Gravity currentslarge-eddy simulationlock-exchangemixingstratification AcknowledgementsThe simulations for this work have been performed using the Aristotle University of Thessaloniki (AUTh) High Performance Computing Infrastructure and Resources.Disclosure statementNo potential conflict of interest was reported by the author(s).Data availability statementData can be provided upon reasonable request to the authors.NotationC=concentration (–)Cave=spanwise average concentration (–)C¯=current volume average concentration (–)D=depth of the fluid in the lock(m)Ed,ν=dissipation energy due to viscosity (m5 s−2)Ed,SGS=dissipation energy due to SGS viscosity (m5 s−2)Ed,num=numerical dissipation energy (m5 s−2)Ed,tot=total dissipation energy (m5 s−2)F=Froude number (–)g′=reduced gravity acceleration (m s−2)H=total fluid depth (m)I=internal energy due to density diffusion (m5 s−2)K=kinetic energy (m5 s−2)L=tank length (m)L0=lock length (m)N=buoyancy frequency (s−1)nc=cumulative mixing efficiency (–)p*=the pressure minus the hydrostatic pressure (kg m−1 s−2)P=potential energy (m5 s−2)P0=initial potential energy (m5 s−2)P0str=initial potential energy due to initial fluid stratification (m5 s−2)Pb=background energy (m5 s−2)Pa=available potential energy (m5 s−2)Rb=Reynolds number (–)S=ambient stratification strength (–)Sc=Schmidt number (–)Sc,t=turbulent Schmidt number (–)Sij=deformation tensor component ij (s−1)Ttr=transition time (s)ub=buoyancy velocity (m s−1)ui (u, v, w)=filtered velocity component of the i-direction (m s−1)Uf=current front velocity (m s−1)W=tank width (m)Xtr=transition distance (m)xf=current front position (m)Γ=molecular diffusivity (m2 s−1)ΓSGS=subgrid-scale molecular diffusivity (m2 s−1)ϵ=dissipation rate (m5 s−3)ν=kinematic viscosity (m2 s−1)νSGS=subgrid-scale kinematic viscosity (m2 s−1)ρc=density of the fluid in the lock (kg m−3)ρ0=density at the top of t","PeriodicalId":54802,"journal":{"name":"Journal of Hydraulic Research","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134948811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of relative curvature radius on erosion and sedimentation patterns in a 90^o bend with and without bendway weirs","authors":"Mohsen Salehzadeh, Mohammad Hemmati, Mehdi Yasi, Stefano Lanzoni","doi":"10.1080/00221686.2023.2242813","DOIUrl":"https://doi.org/10.1080/00221686.2023.2242813","url":null,"abstract":"Bendway weirs are low-level transverse structures constructed on the outer bank of a channel bend to improve navigation, create aquatic habitat and control bend migration. This experimental study was aimed at investigating the erosion and sedimentation patterns in a 90° bend by varying the relative curvature radius (i.e. normalized to the channel width), in the absence and in the presence of bendway weirs, under different flow conditions. A series of flat weirs with relative heights of 30% and 70% were considered. The results indicate that as the relative curvature increases, the erosion near the weirs decreases while the point-bar at the inner bend wall extends. Regardless of the weir height, the increase in the relative curvature leads to a deeper scour depth at the tip of the weirs. Bendway weirs with submergence ratio of 70% are found to be the most efficient in protecting the outer bank from erosion.","PeriodicalId":54802,"journal":{"name":"Journal of Hydraulic Research","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134947882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Air entrainment and free-surface fluctuations in A-type hydraulic jumps with an abrupt drop","authors":"Maoyi Luo, Hang Wang, Xiaohui Zheng, Davide Wüthrich, Ruidi Bai, Shanjun Liu","doi":"10.1080/00221686.2023.2239193","DOIUrl":"https://doi.org/10.1080/00221686.2023.2239193","url":null,"abstract":"AbstractIn high dam construction projects in China, stilling basin design with an abrupt bottom drop is sometimes introduced to reduce the bottom velocity and pressure loads by generating A-type hydraulic jumps. Although the stilling basin design is not new, A-type hydraulic jumps have not been studied taking into account the air entrainment and evolution of internal air–water flow structures. This paper presents an experimental study of self-aerated A-type jumps in terms of bubble transport and free-surface fluctuations over the bottom drop. Four Froude numbers from 4.1 to 10.3 are tested for three drop heights, in addition to the flat-bottom case. Compared to the classic hydraulic jumps, A-jumps are observed with longer jump lengths and weaker free-surface fluctuations. The downward deflection of the jet-shear flow and formation of a bottom roller in the step cavity require a modification to the analytical expression of velocity and void fraction distributions. The relationship between the bubble diffusivity and jump spreading rate differs from that in classic hydraulic jumps, suggesting a faster expansion of the bubble diffusion layer than the turbulent shear flow downstream of the drop, especially for large drop heights. At large approach velocities, the reattachment of the deflected jet-shear flow to the lowered bed may cause a local rise in bubble counts downstream the bottom roller. Further increase in drop height results in a W-jump with overwhelming bottom roller over the surface roller and an arced surface jet, which is beyond the scope of this study.Keywords: A-jumpabrupt dropair entrainmentbottom rollernegative step AcknowledgementThe assistance of Rongcai Tang with the optical flow analysis is acknowledged.Disclosure statementNo potential conflict of interest was reported by the author(s).FundingThis work was supported the National Natural Science Foundation of China [grant no. 52192673, 51939007] and the Natural Science Foundation of Sichuan Province [grant no. 2022NSFSC0970].","PeriodicalId":54802,"journal":{"name":"Journal of Hydraulic Research","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134948608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental investigation on flow of trash rack blockage in front of pumping station","authors":"T. Yan, B. Qiu, Jianping Yuan, Guipeng Qi","doi":"10.1080/00221686.2023.2232755","DOIUrl":"https://doi.org/10.1080/00221686.2023.2232755","url":null,"abstract":"Trash rack blockage significantly affects the water levels and velocity distributions near trash racks, influencing the performance of subsequent hydraulic systems. An experiment was conducted where alligator weeds, green grasses, woven bags, denim, and cotton fabrics were used as typical trash. Under different amounts of trash, approach velocities and water depths, the movement and aggregation characteristics of the trash were observed and measured. The water level difference and the velocity distributions of cross-sections near trash racks were measured and analysed. A general dimensionless expression was advanced to calculate the head loss coefficient of the trash rack. We introduced the local head loss formula of trash rack blockage based on measured velocity distributions. The results indicate that the water level difference is related to blocked trash characteristics and the approach velocity. The velocity distributions are determined by the blocked location and blocked area on the rack surface. Backflow occurs in severe blockage, which makes the velocity distribution uneven and increases the local head loss.","PeriodicalId":54802,"journal":{"name":"Journal of Hydraulic Research","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48988413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating the performance of the modified two-component pressure approach in capturing column separation with large vapour cavities","authors":"David Khani, Y. Lim, A. Malekpour","doi":"10.1080/00221686.2023.2231397","DOIUrl":"https://doi.org/10.1080/00221686.2023.2231397","url":null,"abstract":"This paper investigates the performance of the modified two-component pressure approach (proposed model), recently proposed by the authors, in capturing column separation with large vapour cavities. The proposed model calculates both the cavitating and waterhammer flow regions using a single set of equations that governs unsteady flow in open channels. Comparing the results with experimental data, and the results obtained from the discrete gas cavity model (counterpart model) reveals that: (1) the proposed model can accurately capture the evolution of large vapour cavities in pipe systems; (2) the model provides more accurate results compared to the counterpart model; (3) under some circumstances the counterpart provides inaccurate results as it fails to account for the energy loss in the cavitating flow zone while the proposed model was shown to resolve the issue. Finally, the results exhibit the superiority of the proposed model over the counterpart model and the conventional open-channel-based models.","PeriodicalId":54802,"journal":{"name":"Journal of Hydraulic Research","volume":"1 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44823612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of intake pipe blockage on the critical submergence for lateral dual intakes","authors":"Muhammed Hashid, T. Eldho","doi":"10.1080/00221686.2023.2232763","DOIUrl":"https://doi.org/10.1080/00221686.2023.2232763","url":null,"abstract":"This paper presents an experimental study focusing on the effect of intake pipe blockage on the critical submergence of lateral dual square intakes under perpendicular uniform approach flow. The pipe blockage is implemented by various intake protrusions into the approach flow, with one of the intakes always kept flush with the channel sidewall. An increase in protrusion of downstream intake alone causes a significant decrease in critical submergence, and an increased protrusion of upstream intake alone causes higher critical submergence when both intakes operate under identical conditions. At higher protrusions of twice the intake size, the mutual influence between the intakes was negligible with multiple vortex formations at both intakes in dual configuration. Based on the results, an empirical equation is proposed for the computation of critical submergence for lateral dual protruded intakes and was found to be in good agreement with the experimental results, which will be useful in the design for fixing the invert level of dual intakes under approach flow condition. The flow blockage due to protrusion can be adopted effectively to reduce the critical submergence for multiple intake structures.","PeriodicalId":54802,"journal":{"name":"Journal of Hydraulic Research","volume":"61 1","pages":"573 - 582"},"PeriodicalIF":2.3,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45637723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}